Relaxation oscillation generator



Aug. 8, 1939.

R. BARTHELEMY 2,168,508 RELAXATION OSCILLATION GENERATOR Filed Sept. 24, 1936 'B rf/ e/emy INVENTOR if: ATTORNEY Patented Aug. 8, 1939 r PATENT "OFFICE RELAXATION OSCILLATION GENERATOR Ren Barthelemy, Fontenay aux Roses, France, assignor to Compagnie pour la Fabrication des Compteurs et Materiel dUsines a Gaz, Montrouge (Seine), France Application'September 24, 1936,Serial No. 102,263 In France 0ctober4, 1935 10' Claims.

Itis already known to use cold or hot'cathode electronic discharge tubes'to produce relaxation or saw-tooth oscillations such as are used more particularly toproduce the movement of the luminous point overthe screen in cathode ray oscillographs. The conditions to be fulfilled for the production of a good displacement of the -beam are the symmetry of the deviation from the position of rest and the linearity as a functionof time; these two conditions necessitating in the known systems the use ofspecial tubes and complicated circuits. 7

The present invention has for its object to 'solvethe same problem by simple means.

Itconsists essentially in disposing the linear elements symmetrically with respect to the relaxation member.

Figure 1 shows an embodiment of the invention, the function of which is explainedin Figure 2.

' Figure 3 shows another embodiment of the invention.

' -Figure 4 relates to a variation in the method of controlling the relaxation member.

"As shown inFigure 1, the relaxation element is a gas tube l which may function in the known manner. The discharge therein is initiated if the potential of pthe anode is greater than an upper critical voltage and, once initiated, it only ceases if the potential of the anode falls below a lower critical voltage. The discharge can also be initiated by putting the tube into a conducting condition by the application of a suitable voltage to the grid. It is this latter method which is used. The grid is polarized with respect to the cathode by means of a source 2. The successive discharges are either free or controlled by impulses transmitted, for example, by a transformer 3. The gas-tube l is inserted between the two circuits 4, 4', each comprising a resistance 5, 5' and a 'reactance 6, 6 in series, "shuntedby a condenser 1, 1'. The displacement of the cathode beam is produced by the voltage at the terminals 8 and 9 of the tube l, whilst the feeding of the quadripole is effected from the terminals l8 and H. When the tube I does notreceive any impulse and consequently is not a conductor, the terminals 8 and Ill are at the same potential, and the terminals 9 and II are also at the samepotential. The condensers I and l are not charged. The tension between theterminals8 and 9 is at themaximum. When the tube receives an impulse over the grid, it"becomes'conductiveand the two condensers 1 r and :I are immediately I charged. The potential difference between the terminals 8 and 9 decreases in proportion-as the condensers are charged and attains rapidly the lower critical voltage 01 of the tube I. At this moment the discharge across the tube ceases. By designating with U the voltage applied to'terminals l0 and II and with w and m, respectively, the voltages attained by the condenser l andl, when the discharge ceases, the following equations can be formed:

In order to make the second equation correct, it is necessary that the two circuits 4 and 4' are strictly identical.

When the discharge in'the tube I ceases, the

condensers l and 'l' are discharged relatively slowly across the resistances and inductances 5,

6 and 5', 6. Ifthe twocircuits 4 and 4 are identical, the two discharge curves of the condensers '1 and 1 are'likewise identical. Thus the voltage difference between the terminals 8 and 9 varies from 221 to U. Assumed that the potential of the terminal I0 is zero and the potential of the'terminal H is U, the potential it of the terminal 8 will vary from to zero and the potential it of the terminal 9 will vary from to U. These two variations are represented in Fig. 2 under the supposition that m be zero. Fig. '2 shows, that the variations are symmetrical with respect to 2 The linearityof the variations, 1. e., of the curves 'u. and u. of Fig.2 perfectlysymmetrical; linearityyis obtained due to the use of the reactances 6,8 according to the method described in my to be varied. When the tube 2| does not receive any impulse and consequently is no conductor, the terminals 28 and 3| are at the same potential and so are the terminals 30 and 29. The potential difference between the terminals 28 and 29 at this moment equals the feeding potential U. Both the condensers 21 and 21' are charged with the tension U. When an impulse is received over the grid of tube 2|, the latter becomes conductive. The condenser 21 is discharged into the resistance 25 and the condenser 21 is discharged into the resistance 25'. These discharges are relatively slow and cease completely, when the potential difference between the terminals 28 and 29 falls below the lower critical voltage '01 of the tube 2|. When the discharges cease the condensers 2'! and 21' are recharged immediately to the tension U. It appears, that the potential difference between the terminals 28 and 29 varies slowly from U to 111 and then increases rapidly from m to U. Also in this case, the voltages of the terminals 28 and 29 are symmetrical with respect to as illustrated in Fig. 2, owing to the symmetrical disposition of the resistances 25 and 25.

The. preceding devices use for the displacement of the beam or scanning the discharge of a condenser, but, according to the present invention, the charge may also be used. Such an arrangement is illustrated in Figure 4 as applied to a modification in which the relaxation element 6| is a high vacuum tube, for example, a triode, having a low internal resistance.

The vacuum tube BI is connected to the terminals of the relaxation condenser 61, charged by a continuous current through resistances 65 and 13. A potentiometer 62, H, of high resistance serves to polarisethe grid of the tube 6!; the positive part H1 of this potentiometer is shunted by a gas discharge tube 12 in series with the resistance 16; the operations of T2 are controlled, through the intermediary of the coupling 63, by the synchronizing impulses. Then the condensers 11,, 11 are employed to supply the deflecting plates of the cathode tube.

I It will be seen that the gas discharge tube 12 plays in this arrangement the part of an on and. off relay, each of its operations resulting in the shunting of H1, by the resistance 16 thereby rendering the grid of the tube 6| positive. Once the discharge has taken place, the time during which the grid of the tube 6| remains positive can be regulated by the condenser 15 and the resistance 13; the elements 12, 15 and 52 form moreover a relaxation circuit having a relatively long period which assures an operation of the tube 6| at the end of a certain time even in the absence of the synchronising signals.

The invention is so particularly applicable to the known cathode tube scanning systems for television in which the signal synchronising the images consists of the periodic suppression of a line signal. It has moreover the followingadvantages; use of the gas discharge tube at feeble load whereby a long period of service is secured; a very reduced consumption at high-tension which enables a common feeding source with the cathode tube to be employed.

With a view to assuring the quick extinction of the tube 12 it will be advantageous to connect to itsterminals a small capacity 15'' (the parasitic capacity of the apparatus may suffice in certain cases) What I claim is:

1. Device for the production of relaxation oscillations, comprising a discharge tube, at least a cathode, an anode and a control electrode in said discharge tube, means for impressing impulses of voltage to said control electrode, two terminals to be connected to a feeding source, a first circuit comprising a resistance and connected between one of said terminals and the anode of said discharge tube, and a second circuit identical to said first circuit connected between the other terminal and the cathode of said discharge tube, whereby the time variations of the voltage of the said cathode and of the said anode are symmetrical with respect to the mean feeding voltage.

2. Device for the production of relaxation oscillations, comprising a discharge tube, at least a cathode, an anode and a control electrode in said discharge tube, means for impressing impulses of voltage to said control electrode, two terminals to be connected to a feeding source, a first circuit connected between one of said terminals and the anode of said discharge tube, a condenser and a resistance in said first circuit, and a second circuit identical to said first circuit connected between the other terminal and the cathode of said discharge tube, whereby the time variations of the voltage of the said cathode and of the said anode, due to the charges and discharges of the condensers in said circuits, are symmetrical with respect to the mean feeding voltage.

3. Device for the production of relaxation oscillations, comprising a relaxation element, two first terminals to pick-up the relaxation oscillations and connected to said relaxation element, two second terminals to be connected to a feeding source, a first oscillating circuit connected between one of the first terminals and one of the second terminals, and a second oscillating circuit identical to said first circuit and connected between the two other terminals, whereby the time variations of the voltage of the two first terminals are symmetrical with respect to the mean feeding voltage.

- 4. Device for the production of relaxation oscillations, comprising a discharge tube, at least agcathode an anode and a control electrode in said discharge tube, means for impressing impulses of voltage to said control electrode, two terminals to be connected to a feeding source, a first circuit connected between one of said terminals and the anode of said discharge tube, a resistance and an inductance in series in said first circuit, a condenser connected in parallel with said resistance and inductance in said first circuit, and a second circuit identical to said first circuit connected between the other terminal and the cathode of said discharge tube, whereby the time variations of the voltage of the said cathode and of the said anode, due to the charges and discharges of the condensers in said circuits, are symmetrical with respect to the mean feeding voltage.

5. Device for the production of relaxation oscillations, comprising a discharge tube, at least a cathode, an-anode and a control electrode in said discharge tube, means for impressing impulses of voltage to said control electrode, two

terminals to. be connected, to a feeding source, a

first circuit connected between the positive one of said. terminals and the anode of said discharge tube, a resistance in said first circuit, a second circuit identical to said first circuit connected between the negative terminal and the said cathode, a first condenser connected between the anode of the discharge tube and the negative terminal, and a second condenser connected between the cathode of the discharge tube and the positive terminal, whereby the time variations of the voltage of the said cathode and of the said anode, due to the charges and discharges of the said condensers, are symmetrical with respect to the mean feeding voltage.

6. Device for the production of relaxation oscillations, comprising a discharge tube, at least a cathode, an anode and a control electrode in said discharge tube, a condenser connected between said anode and cathode, two terminals to be connected to a feeding source, a first circuit comprising a first resistance connected between said anode and the positive one of the said terminals, a second circuit identical to said first circuit comprising a second resistance and connected between said cathode and the negative one of the said terminals, a second discharge tube, a coupling member receiving the signals and connected to said second discharge tube whereby a discharge is set up in the said second tube by each signal, means for connecting the second tube to the control electrode and to the cathode of the first tube whereby, when a discharge takes place, the voltage between said control electrode and said cathode is modified, rendering the first tube conductive and provoking the discharge of the said condenser, the time variations of the voltage of the said cathode and of the said anode being symmetrical with respect to the mean feeding voltage, due to said first and second circuits connection.

7. Device for the production of relaxation oscillations, comprising a discharge tube, at least a cathode, an anode and a control electrode in said discharge tube, a condenser connected between said anode and cathode, two terminals to be connected to a feeding source, a first circuit comprising a first resistance connected between said anode and the positive one of the said terminals, a second circuit identical to said first circuit comprising a second resistance and connected between said cathode and the negative one of the said terminals, a third resistance connected between the two said terminals, a connection between said control electrode and an intermediate top on said third resistance for the polarization of the said control electrode, a second discharge tube, a coupling member receiving the signals and connected to said second discharge tube whereby a discharge is set up in the said second tube by each signal, means for connecting the second tube to said third resistance whereby when a discharge takes place, a part of the third resistance is shunted, whereby the polarization of said control electrode is modified, rendering the first tube conductive and provoking the discharge of the said condenser, the time variations of the voltage of the said cathode and of the said anode being symmetrical with respect to the mean feeding voltage, due to said first and second circuits connection.

8. Device according to claim 6 in which the second discharge tube is a gas discharge tube having a control electrode, the said coupling member being inserted in the circuit of the said control electrode of the second discharge tube.

9. Device according to'claim '7 in which the second discharge tube is a gas discharge tube having a control electrode, the said coupling member being inserted in the circuit of the said control electrode of the second discharge tube.

10. Device according to claim 7 in which a part of the said third resistance is shunted by a condenser in order to obtain self-sustained oscillations.

RENE BARTHELEMY. 

